The invention relates to systems and methods for ablating the interior regions of the heart for treating cardiac conditions.
It is believed that lesions larger than those created by current electrophysiological therapy are needed to more consistently cure myocardial ventricular tachycardia (MVT) of ischemic origins.
Conventional cardiac ablation systems designed to cure re-entrant supra ventricular tachycardia (SVT), often create lesions in myocardial tissue with a penetration depth of about 3 to 5 mm and a lesion volume of less than 0.2 cm3, depending upon the size of the electrode and the amount of power that is applied.
However, to consistently cure MVT by ablation, a penetration depth greater than 3 to 5 mm and a lesion volume of at least 1 cm3 is estimated to be required.
The solution lies in larger electrodes. Yet, larger electrodes themselves pose problems of size and maneuverability that weigh against safe and easy introduction through a vein or artery into the heart.
A need exists for cardiac ablation catheters having that flexibility and maneuverability that permits safe and easy introduction into the heart and, once deployed inside the heart, emit energy sufficient to cause permanent, irreversible thermal damage to large regions of myocardial tissue.
The invention provides a cardiac ablation catheter having an energy emitting surface for thermally destroying tissue. The surface normally presents a compact, low profile for introduction into the heart.
Once introduced, the energy emitting surface can be significantly enlarged. The enlarged surface emits ablation energy sufficient to create a lesion that is significantly larger in terms of volume and geometry than the surface""s initial low profile would provide.
The catheter of this invention is configured to produce lesions with a greater surface area, compared to standard cardiac ablation catheters, while maintaining a standard (6, 7, or 8 French) introducer size (a xe2x80x9cFrenchxe2x80x9d equals 0.013 inches).
The enlarged surface area creates larger lesions, since the lesion volume and geometry are factors which are controlled according to the shape and size of the energy emitting surface.
In accordance with a further aspect of the invention, an inflatable surface is produced using a thermoplastic polymeric material such as polyethylene. The inflatable surface is coated, all or partially, with an energy emitting material. When deflated, such a surface presents a compact profile. When inflated, the same surface has an significantly enlarged dimension of, for example, approximately 7 to 12 mm.
Another aspect of the invention is an expandable energy emitting surface with an associated temperature sensor.
In an alternative arrangement, the expandable surface can also be used for obtaining electrogram recordings or for similar mapping procedures.
The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims.